Applications, systems, and other resources may expose functionality as a service, such as a web service, that can be invoked by another application, system, etc., for example by making a function or other call in to the service. Typically, an API, web services definition, etc. is provided to define and describe the manner in which such service calls are required to be made.
Typically, the called service requires a finite amount of time to perform and complete processing required by the call, and to form and return a response. The calling application, process, etc. may be blocked from performing other tasks until a response to a service call is received. If the latency is relatively high, the efficiency and throughput of the calling application may be impacted adversely, particularly if the calling application has a single thread architecture.